1. Field of the Invention
This invention relates to a washout arrangement for a well, in particular for washing out the annulus surrounding a casing hanger when installing a well casing at the mudline with a jackup drilling rig.
2. Description of the Prior Art
In such installations, it is typical to use large diameter, say 30 inch (760 mm) diameter conductor which will extend from the drilling rig to a selected depth in the well. The operator will drill the well to a greater depth and install a surface casing within the conductor.
A casing hanger will then be secured to the upper end of the surface casing and this casing hanger will land on a shoulder in the conductor, approximately at the mudline. A running tool is secured to the top of the casing hanger and is used to lower the casing hanger and casing string down the well. In order to secure the surface casing string in the drilled well, cement is pumped down the casing string to return up the annulus between the casing and the drilled walls of the well and, at upper end, between the surface casing and the conductor.
After cementing, the operator will need to wash out the casing in the annulus area surrounding the casing hanger. One system which is often used makes use of washports in the casing hanger, these ports being covered up by the overlap of the running tool with the casing hanger, when the running tool is engaged with the hanger. To open the washports, the running tool is partly disengaged from the casing hanger, and water or other fluid is then pumped down the well to flow out through the washports, to flush out cement from the annulus surrounding the washports, and to clear the annulus above the washports of cement.
It is known from EP 0 272 080 to locate the washports in the running tool and to have an internal lower body within the running tool which can move up and down to open and close the ports. The operator runs a torque tool from the drilling rig down to the running tool. The torque tool engages a slot on the internal lower body and the operator rotates the torque tool. As the lower body is secured by threads to the running tool, the rotation causes the lower body to move axially upward or downward, depending on the direction of rotation of the torque tool.